


You're in Over Your Head, Jean Kirstein [Sigmaverse]

by Jean_Kirstein_Is_My_Waifu



Series: Jean Kirstein x Reader [1]
Category: Shingeki no Kyojin | Attack on Titan
Genre: Alpha Jean Kirstein, Alpha/Beta/Omega Dynamics, Alternate Universe - Soulmates, Because there is a need for Jean/Reader fics, F/M, I'm Bad At Tagging, I'm Sorry, Jean Is A Little Shit, My First AO3 Post, Sigma Reader, Sigmaverse
Language: English
Status: In-Progress
Published: 2017-10-24
Updated: 2017-11-06
Packaged: 2019-01-22 01:56:16
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 2
Words: 4,052
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12470904
Author URL: https://archiveofourown.org/users/Jean_Kirstein_Is_My_Waifu/pseuds/Jean_Kirstein_Is_My_Waifu
Summary: Sigmas were anomalies.  They could turn anyone, no matter powerful, into their pawn.  Alphas quaked in fear, and yet when they tried to eliminate the few Sigmas, they failed.Because Sigmas were always one step ahead.You were always one step ahead.And as Alpha Jean Kirstein found out if you can’t beat ‘em, kindly ask them to team up and maybe they won’t weave you into their web of lies. Maybe.ORAlpha Jean Kirstein falls for the mysterious Sigma from the 103rd Training Corps.ORThat altered Omegaverse AU/ Sigmaverse AU/ Soulmate AU that no one asked for.I apologize in advance.  I’m sorry.Alpha! Jean Kirstein X Sigma! ReaderP.S- School is in full swing and I may not have time to update as much as I like, but updates will be coming!





	1. Overture

**Author's Note:**

> I maybe possibly had an idea for a fanfic after taking a wolf hierarchy test and I found out that I'm a Sigma, so for all the Jean Kirstein loving Sigmas, this is for you!

“Jean Kirstein, I know you’re there,” you grumbled, not looking at the ashen-haired boy and crossed your arms as he slinked onto the porch. “There is about a 95 percent chance you’re shirtless and a five percent chance you’re not. Of that five percent, there is a 33 percent chance that your shirt has at least three buttons unbuttoned and a 67 percent chance that your shirt is not buttoned at all.” When you turned around to face him, his eyes widened in awe, his cheeks stained pink, and his white buttoned up shirt tied around his waist. Sweat gleaming on his chiseled abdominals and goddammit you did not need that at the moment.

  
“What the--” he began, raising his eyebrow at your factual rambling.

  
“I could smell you from a mile away. Put on your shirt, goddammit,” you scolded him, watching the poor boy swiftly dawn his shirt.

  
You planted your feet firmly on the ground, arms folded as he took his good ol’ time placing the buttons in their rightful holes.

  
“Why are you here?” you asked after he had finally finished dressing.

  
“Heichou told me to tell you that the due date for the Human/Titan behavior paper that you and Hanji are writing has been pushed back for another two weeks.”

  
“Oh, well, I’ll let her know. Thanks, cadet--wait! Did you hear that?” you asked, smirking at Jean.

  
“What? Is it bad?”

  
“Oh no, it’s just Hanji. There is a 99 percent chance that she’ll be out here in twenty-four point three-four seconds, and there’s an 82 percent chance she’ll call me, and a 90 percent chance that if she does, she’ll more than likely say it in a way that would require a tilde after the exclamation point if someone was writing dialogue down.”

  
“And that means--”

  
“Y/NNNN!~ There you are! Any news on the due date for our Human/Titan behavior paper?” Hanji asked, popping her head out the window, her brunette hair in a messy bun.

  
“Kirstein said that it’s been pushed back two weeks” you replied, gesturing towards the boy who still looked as out of place as ever.

  
“Fabulous! This gives us more time to conduct more experiments and gather more data and collect--” Hanji rambled excitedly, walking into your shared office space and slamming the door.

  
“Well cadet, do you have any more business--?” you asked as you spun on your heels, but Jean already disappeared.

The first time you met Jean was the first day of training for the 104th corp. You observed from the porch of the dining hall and judged the poor excuse of an Alpha pathetically enlarge his sad puppy dog eyes to Mikasa Ackerman as she left the dining hall two steps behind and slightly to the left of Eren Jaeger.

  
“Give it up kid. She’s already taken,” you grumbled as you watched the drool practically flowing out of his wide-open mouth. Jean surprisingly tore his eyes away from Mikasa for a minute to shoot you a cold glare.

  
“Who the hell do you think you are, talking to an Alpha like that?” he asked, stepping towards you with bravado.

  
“Who cares if you’re an Alpha,” you replied cooly as you shook your head, “I’m from the 103rd Training Corp. I’m your superior here. This is the military, cadet, not civilian society,”

  
“You’re the strangest smelling Omega I’ve ever met,” he replied, crossing his arms defensively and recoiling back.

  
“Who said I was an Omega?” You retorted, lips curling into a smile to show off your fangs.

  
“Whatever. I don’t have time for this,” Jean huffed, avoiding your fiery eyes and quickly scooting away to avoid any more insults.

  
“Alright then. See ya around, Jean Kirstein,” you replied loud enough for him to hear. Jean whipped his head back, terror plastered to his face. A “How did you know his name?” was probably running through his head right about now (you were 99 percent sure). You were almost sure he was going to ask, but you never gave him the chance as you disappeared into the shadows, making your way back to your bunk.

  
This kid was going to be fun.

* * *

 

You made haste migrating back into your office, the sounds of Hanji’s rambling ricocheting off the walls.

  
“We’ll have to try to capture some titans to experiment on. I swear if it wasn’t for that Annie girl we could have--”

  
“Hanji.”

  
“--definitely had that paper all finished! It's a shame, really. But nonetheless, maybe we can get Levi--”

  
“Hanji.”

  
“--to capture one for us? Ahh, who am I kidding? Levi’s been pretty adamant--”

  
“Hanji.”

  
“--about not capturing titans for me. Some mate, am I right or--”

  
“ZOË, PLEASE JUST SHUT UP!” You finally yelled, silencing the scientist as you plopped down on your chair behind your desk with exhaustion and rested your head on your desk with a sigh. “We have two more weeks. I’m sure Levi’ll understand if we take off a day or two,” you reasoned.

  
To say you were tired was an understatement. You felt as though every single cell of your body was shutting down, especially after listening to Hanji’s tangent bouncing off the walls of the cramped office.

  
“You can’t keep ignoring it, Y/N,” Hanji said as she shuffled a few papers on your desk. “That Jean Kirstein is your mate, isn’t he?”

  
“I have no idea what you’re talking about Hanji,” you replied, trying to avoid the question.

  
“Don’t play with me, kid. I’ve known you your whole life. Don’t think you can pull the wool over my eyes now,” Hanji replied, her bubbly façade long gone, reminding you that she was humanity’s scariest when she wanted to be.

  
“Hanji, really, he’s not--” you began before Hanji rolled up the right sleeve of your shirt, revealing the two words that you insisted weren't there. _Jean Kirstein_.

  
“How long?” Hanji asked as she released your arm roughly and leaned on her right hip while crossing her arms.

  
“When I graduated the Training Corps, so about a year,” you replied, your voice growing faint as you placed your head into your hands. “of all the assholes here, he just had to be mine?” you grumbled as you lifted your head up to meet Hanji’s gaze.

  
“Don’t look at me kid. I got Levi. _Levi_. You know, Captain Grouchy-Pants? Kirstein can’t be that bad.”

  
“Oh, but it get’s worse.”

  
“I highly doubt it, but shoot.”

  
“He’s madly in love with Mikasa. Has been since he started training. He even ignores the fact that she’s practically bound to Eren. I’ve seen her mark, clear as day. Eren Jaeger, not Jean Kirstein. I’m not dealing with that. Besides, have you seen the mortality rates for the Survey Corps? It’s too high, and I’m not going to get attached to some Alpha who won’t give me the time of day, thank you very much.”

  
The two of you sat in silence for a long while. You looked out the window as big, white, fluffy clouds floated in the sky. It was times like this when you wish you could just forget about the world, the Titans, the walls, everything.

* * *

 

You were almost eleven when your parents, two Omegas from wealthy Alpha upbringings, journeyed from the comfort of Wall Sina to the Shiganshina region for business purposes. You, the youngest of three kids and the only girl, was to be left with your older cousin while your mother, father, and brothers went on their merry way. You weren't happy- you had wanted to tag along with your family- but then again, who wouldn’t want to spend months-on-end with your favorite cousin?

So, at age ten and nine months, you found yourself standing at the front door of the Survey Corp Headquarters, waiting for your cousin. A short man appeared from inside the door, his eyes squinting down at you.

  
“Hanji, I think that little demon that you’re babysitting is here,” the man said before a loud ear-piercing squeal ruptured through the air.

  
“Y/NNNNN!~” squealed you cousin, Hanji Zoë as she barreled over the man to give you a hug.

  
“Ignore Levi, he’s just jealous that he doesn't have a super-cute little cousin like you!”

  
And with that, Hanji dragged you to her lab to show you her life’s work.

It was during your second day at the Survey Corp that you found your passion- human behavior. It started with Hanji, who just had to brag about you, her ‘super cute and extra smart little cousin’, to all of her co-workers. You had never been around so many people before and you weren’t the most social person, so you loved to just watch them. It was the most interesting thing to you, which didn’t surprise Hanji at all. She handed you a notebook a week later and told you to you write down your observations.

  
You filled it out in two days.

  
Hanji showed Levi your work, bragging about you to him saying she had the ‘best, coolest little cousin ever’. That’s when you came tumbling into her room, showing off your latest find; a Sigma _Σ_ on your shoulder, symbolizing your place in society.

  
You were a Sigma and boy was Hanji thrilled. Sigmas were anomalies. They could turn anyone, no matter powerful, into their pawn. Alphas quaked in fear, and yet when they tried to eliminate the few Sigmas, they failed.

  
Because Sigmas were always one step ahead.

  
Both you and Hanji, being typical Sigmas, were one step ahead, much to Levi’s annoyance and slight horror.

  
And for the first two months, you were as happy as you ever were in your short life.

  
And then, Shiganshina fell.

* * *

 

Hanji and Levi returned from a trip outside the walls only a few hours prior, returning with presents from your family for your upcoming birthday. They were both emotionally and physically tired and exhausted from their journey, and you knew not to pry- expeditions were rough on both of them. You sat, watching the rest of the Survey Corps recover, writing frantically in your ninth notebook.

  
Then, there was a loud wail of a siren pierced your ears, causing you to stand on your tiptoes and look out the window.

  
Wall Maria had fallen.

  
You ran back to Hanji and Levi, as you shoved your belongings into a few bags.

  
Wall Maria had fallen.

  
“What the hell are we going to do?” You asked Hanji as the two of you ran, Levi on your heels.

  
“We get the hell out of here, that’s what,” Levi yelled back, shoving you into a cart with Hanji.

  
Your family was dead.

  
They were all dead, and there was nothing you could do. You felt hopeless as the cart you were piled in took off, speeding away from the old headquarters, watching your old life be crushed by the Titans.

  
The next year, much to Hanji’s horror, you joined the 103rd Training Corps, with every intention of joining the Survey Corp.


	2. Jean Kirstein Needs to Learn How to Wear a Shirt

**Summary for the Chapter:**

> Y/n now has an assistant, and he can't keep his shirt on.

**Notes for the Chapter:**

> Hey! So, I was really surprised how many hits this got, which is almost 80!!! in about two weeks. I was expecting maybe 10 or so tbh since this is my first work. I'll try to update about once a week, maybe Tuesdays or Wednesdays, but I've got school so that may change!  
> Anyways, here's the next Chapter! Enjoy!

“Levi, you’ve got to be kidding me,” you grunted, looking at the shorter man in disgust, bringing your hand to your forehead.  He looked back at you with those trademark dead-inside eyes of his that you hated.

“Nope.  Why would I joke about something like this?” He chuckled with a sarcastic grin slowly spreading across his mouth.

“ARRRGH! HANJI! PLEASE TELL ME HE’S JOKING!” You yelled at your cousin who popped her head out of your shared office door to see what the yelling was about.

“You know Levi.  He’s not really a ‘joker’.  Sarcastic, yes, but a joker?  No,” Hanji replied as she walked over to you, “besides, shouldn’t you be happy about this?”

“No!  I couldn’t stand the guy when he was in the Training Corps, and now he’s going to be my assistant?  Of all the new recruits, why not Armin?  He has a brain, unlike this kid!”

“Oh shut up, Y/N.  Sure, Kirstein is an ass, but he’s not that bad,” Levi reasoned.

“I’ll go to Erwin--I’m sure he’ll get this sorted out,” you announced as you began to leave Levi in search of Erwin, but stopped after feeling a tug on your sleeve.

“Just give the kid a chance.  I’m sure he’ll be fine,” Levi pleaded ( _ wait, pleaded?) _ , going as far as to give you  _ puppy dog eyes? _ Nope, you were just imagining things.  You  _hoped_ you were imagining things.

“Fine!  One week.  That’s all.”

* * *

 

With your eyes bloodshot and dark circles lying underneath, you trudged through the mess hall sporting the Don’t-Talk-To-Me-Before-I’ve-Had-My-Coffee look.  Breakfast that morning moved quickly without your mental presence as you went through your morning routine--cereal with 2% milk and honey, a banana, and a coffee.  You migrated to your regular seat, alone in the back corner of the room, as you pulled out the 301st volume of your notes accompanied by your fountain pen with your bottle of ink, a gift from Hanji and Levi for your sixteenth birthday. You gingerly touched the tip to the ink to fill up the pen, taking care of delicate point as to not harm it, then screwed the cap on the pot of ink.  After this, you finally settled and began to write.

_ October 29th, 850. _

_ Sasha Blouse never ceases to amaze me.  The fact that she can eat so much and yet stay so slim is very impressive.  Note: watch her workout routine for any abnormalities.  If none arise, take her in and run a few tests. _

_ Armin Arlert has his nose in a book again.  He seems to be fascinated on the Titan subject, but then again, who isn’t?  This is the Survey Corps after all.  Note: get him to work with Hanji on a research paper? _

_ Eren Jaeger is being cocky (as usual).  There’s a 99.9% chance he’ll get a rise out of Kirstein today. A fight will then ensue, with Kirstein trying to prove his worth to Mikasa, but, as usual, he will fail.  It's really pathetic. _

_ Mikasa Ackerman is rolling her eyes at Eren’s behavior.  She does this on a regular bases.  REMINDER- Get this girl in for some tests.  Examine her genetic sequence and compare with Levi’s. What makes this kid tick?  Could be the key to-- _

“Hey,” a familiar voice said, startling you from your observations. “Can I sit here?”

_ Jean Kirstein. Of freaking course. _

Jean Kirstein was  _ here _ , in front of  _ you _ , holding his breakfast tray, which consisted of eggs and toast, asking you if  _ he _ could sit here.  With  _ you. _  Not demanding,  _ asking _ .

Well, color yourself confused.  This  _ clearly _ wasn’t in your calculations. Kirstein never passed up an opportunity to fight with Jaeger or throw around his weight as an Alpha.

“Aren’t you going to annoy Jaeger or try and win Mikasa’s heart?” you squinted at him as you flipped through the pages of your notebook, “there hasn’t been a time since you first joined the military, back when you were just a cadet, that you haven’t fought with him.  I’ve got evidence if you don’t believe me.”

“......”

“Did that sound stalker-ish?  It did, didn’t it?  I’m sorry, have a seat,” you said, gesturing to the seat across from yours.

“Are you always this flustered?” he asked as he stuffed a roll into his mouth.

“Yeah.  You see, I find humans simply fascinating.  The way they act, what makes them do the things they do, how exactly they tick, I fall in love with them more and more every day.  But when they notice me from my little corner of the world?  Ha, they’re not so much fun after that.”

“Social anxiety?” He ventured, his eyebrows raised slightly.

“Yeah,” you replied, shoveling more cereal into your mouth. 

“Anyways, now that you're my boss…”

“Oh right, that.  I never took you for the guy to be into lab work and such.  Why the sudden interest?”

“Pays well,” was his reply.

“Fair enough.  We’ll go to the office after lunch.  Zoë and I--”

“Zoë?”

“Hanji.  I call her Zoë.  It’s easier since we’re technically both Hanjis.”

“What?”

“Hanji and I are cousins.  Our fathers were brothers. She’s Hanji Zoë and I’m Hanji Y/N.  But no one calls me Hanji since Zoë was here first.  So she’s Hanji and I’m Y/N.”

“Uhhh….”

“Just flow with it man.  Anyways, where was I? Oh right!  _ Hanji _ and I normally stay in the lab for about two hours in the morning, and then do a rigorous three-hour Omni-Directional Gear training session.  After that lunch and then back to the lab until dinner.  Sometimes we pull all-nighters with our studies.  Ready to lose hours of sleep in order to understand the insuperable enemy?”

“Insuperable?”

“Incapable of being overcome or solved. Insuperable. I-n-s-u-p-e-r-a-b-l-e,” you replied, as you went back to your notes.

_ \--Could be the key to the downfall of the Titans.  Side project: Find out how exactly Levi and Mikasa are related, and force them to do fun family bonding projects.  Make a scrapbook. _

“You know, I highly doubt that Levi will be up for ‘family bonding’ anything,” Jean said, his head tilted to read your notes, “you have anything about me in there?”

“Any of my volumes starting at the 117th to 220th will have you in it, and then the 274th to 301st volumes as well.”

“Three hundred and one? How?”

“I started in April of ‘45.  I go through 4.5 notebooks a month, give or take.  Do the math,” you replied, going back to your writing.

_ Jean Kirstein, against all calculated odds, somehow managed to not fight with Eren for Mikasa’s hand in marriage today- _

“I’m not trying to win her hand! I just--”

“Child, you look at her like a wolf looks at their mate.  And stop reading my notes.  It’s weird,” you grumbled as you shut your book. “Are you finished with your breakfast yet?  We’ve got to go.”

“Uh yeah.  I’m all set,” he replied as you got up to throw your trash away, him following directly behind.  You both tossed your trash in the garbage by the door before leaving through the door.

“What happened to you?” you asked Jean once you two were on your way to your office.

“Hmm?”

“I mean, back when you were in the TC you were such a cocky brat, throwing around your title and all that jazz.  And now look at you.  You stay quiet--for the most part at least--and you take orders now.  You’re not who you used to be, Kirstein.”

“And why do you even care?” he asked, shooting you an annoyed glare.

“I care because I’ve never seen someone change like this.  What happened?”

The two of you rounded a corner.

“I’d rather not talk about it.”

“I respect that,” you replied as you flung open the door into the science wing, “welcome to Lab Hanji.  Please don’t touch anything.  You may die.”

“I’ll keep that in mind,” he said as the two of you began to walk down a row of shelves with various chemicals and scientific experiments. You continued until you realized that you no longer heard Jean’s footsteps.  You turned around to see him fixated on a bloody pair of glasses.

“Why is this here?” he asked you as you joined him.

“Oh, it was a murder weapon,” you replied before grabbing his wrist to lead him away.

“Never heard of that being used as a murder weapon before,” Jean stated as he was pulled away from the storage shelves and to where your office was.  You kicked open the door, dragging Jean in along with you as Hanji looked up from her work.

“Y/n! Finally!  I have some more data to be analyzed.  Come on!  Chop chop!”

* * *

“You have got  to be kidding me,” Jean panted as he carried a tall stack of books from the scientific library that lied adjacent to the lab. “exactly why do you need all of these?”

“Cross-referencing,” you replied, wildly scribbling down numbers and figures in a notebook, “so if the Titan’s go for the largest number of people possible, and we know this because--” you thought aloud when a loud ding! reverberated through the room.

“What was that?” Jean asked, looking for the source of the noise.

“That’s the bell for Omni-Directional Gear training,” you replied as you got up from your seat and made your way to the lab’s door. “you coming?”

“Yeah, yeah.  How long is this again?” he asked as joined you, turning out the light before closing the door.

“Three hours.”

“ _ Three hours? _ ” he asked, his jaw dropping to the floor.

“Yeah, three hours.  With Levi too.”

“ _ With Heichou? _ ” another jaw drop.

“Yeah.  How else are we supposed to be the best?” you asked, raising an eyebrow at the shocked cadet.  

You watched him gulp, his Adam's apple bobbing up and down.   _ Damn that boy _ .

* * *

 

“You’ve got to be kidding me.”

“You’ve been saying that a lot lately.  And, no.  Does it look like I’m joking?” 

“Just--you want me to--”

“Yes, I want you to scale the training wall.”

“ _ Without my Omni-Directional Maneuver gear? _ ”

“Oh hey, is that Mikasa over there?” you asked, turning your head and putting your hand over your eyes to block out the sun.  

When you turned around, Jean was halfway up the wall, his trapezius and lateral muscles gleaming with sweat and  _ when did that cheeky bastard take off his shirt _ ?

“Hey, Mikasa! Bet Jaeger can’t do this!” Jean called when he reached the top a few moments later.

“You know she was never here, right?” you asked him. He glanced downwards, only to see that you were no longer on the ground.

“Try behind you, dumbass,” you said sarcastically, causing him to spin on his heels as he turned to face you.

“What?--How did you--I mean--what?”

“I’ve been doing this for a long time kid.  You get used to it,” you began before throwing his shirt in his face, “and if you’re going to be my assistant, no more stripping, capisce?”

Jean’s eyes widened before quickly donning his shirt, his cheeks once again stained pink.  You took this time to scrutinize his right arm, which to your slight satisfaction bore no soulmate name.  Your eyes wandered towards his chest,  _ damn those chiseled pectorals and good lord those--. _

“Ahem. Earth to Y/n?” Jean asked, waving his hand in front of your face. “yes, I know I look good, but pictures last longer,” he smirked, throwing his arm around you.  

You shoved him off you, causing him to lose his balance and almost fall off the wall if it wasn’t for your quick reflexes that caught hold of his hand and hoisted him back up before he knew what hit him.

“What the--”

“I want you to die a cooler death, Jean Kirstein,” you replied with a slightly flirtatious smile. “How pathetic would that sound? ‘Here lies Jean Kirstein, died falling off a wall because he was bad at flirting.’”

“Yeah, yeah.  Can we use the Omni-Directional Maneuver gear now? I want to give Levi a run for his money.”

“Good luck with that, Kirstein,” a voice grumbled from the bottom of the wall.  

The two of you looked down to see Levi, in all of his short glory, scowl up at you. 

“If you two would  _ kindly _ stop  _ flirting _ for maybe just ONCE IN YOUR LIFE AND GET THE HELL DOWN HERE AND GET SOME GOD--Mrmmph mmrmph mmmrrrmph!!!” 

“Levi, you need to learn how to control your anger,” Hanji chirped, her hand clasped to his mouth.  

He shot her a dirty glare. 

“Awwe, I love you too my little honey-bunny.”

You sighed and made your way down the training wall by latter, Jean following behind you (as always).  Hanji, that cheeky little shit, gave you a wink with a smirk, to which you replied with an eye-roll and a stuck out tongue.  Very unprofessional, you know, but you can’t help it.  

Hanji beckoned you to come closer.  You glided over, Hanji pressing one of your Omni-Directional blades in your hand that she had just finished sharpening, and leans closer to you her mouth is right by your ear.

“That Jean Kirstein-- he’s a looker and a keeper.”

This was going to be one long ride.


End file.
